Typically, cylindrical parts are produced by machining a workpiece and then, if necessary, grinding the workpiece.
Attempts have been made to develop high material removal rate (MRR) grinding processes. For example, high MRR outside diameter (OD) grinding processes have been developed as “high speed grinding” processes. Commonly, these high speed OD grinding processes use wheel speeds on the order of 120 meters/second (m/sec) to 300 m/sec, with the general approach of using the higher wheel speed to improve performance. These high speed OD grinding processes typically involve superabrasive (SA) grinding wheels composed of diamond or boron nitride and often having a metal bond, e.g., an electroplated metal bond.
These conventional grinding processes have employed a 100% oil coolant at high pressure to reduce friction, to induce lubricity in the metal-to-metal contact surfaces, and to prevent thermal damage and residual stress to the workpiece. To prevent occasional sparks that could present a fire hazard, these grinding processes typically use a substantial excess of the oil coolant to immerse the grinding zone with the coolant. Large quantities of chips are produced, are directed into the oil coolant, and are difficult to remove, necessitating complex and expensive waste disposal.
In spite of these limitations, high speed OD grinding is practiced on occasion to replacing traditional machining (e.g., turning, milling, or turn broaching). However, application of high speed OD grinding has been limited to small volume part production. In high volume production, the disadvantages of high speed OD grinding are compounded by another serious constraint of the process—the gradual and constant wear of the superabrasive grains, e.g., cubic boron nitride grains. The gradual and constant wear can lead to constant changes in part quality, especially in the case of long cylindrical parts such as, for example, crank shafts. Furthermore, large volume production is not suited to on-line dressing of superabrasive grinding wheels made of galvanic processes. Such wheels are generally used for high speed cylindrical grinding applications with high MRR. This poses another constraint to the implementation of large volume production using high speed OD grinding.
Therefore, there is a need to develop new grinding methods overcoming or minimizing one or more of the shortcomings associated with conventional processes, such as high speed OD grinding.